Purified mCPBA is a useful reagent for the oxidation of several classes of aldehyde. Although linear unbranched aliphatic aldehydes are oxidized to the corresponding carboxylic acids, α‐branched ones undergo Baeyer–Villiger oxidation to formates. α‐Branched α,β‐unsaturated aldehydes provide enolformates and/or epoxides, which can be saponified to α‐hydroxy ketones with shortening of the carbon chain by 1 carbon. Unbranched α,β‐unsaturated aldehydes undergo an interesting Baeyer–Villiger oxidation/epoxidation/formate migration/BV oxidation cascade, which results in formyl‐protected hydrates with an overall loss of two carbon atoms.

Matteson homologations of chiral boronic esters proved to be an excellent tool for the synthesis of highly functionalized amino and hydroxy acid residues. This method provides straightforward stereoselective access to the side chain of callipeltin A, a natural marine product with interesting biological activities. Furthermore, this protocol should allow for variations in the substitution pattern in future SAR studies, simply by choosing suitable nucleophiles during the homologation steps.

N-(α-Hydroxyacyl)-glycinesters can be used as excellent nucleophiles in Pd-catalyzed allylic alkylation. The method allows for the stereoselective introduction of a wide range of side chains, including highly functionalized ones. Both diastereomers can be accessed through variation of the reaction conditions. Furthermore, the use of stannylated carbonates introduces vinylstannane motifs, which are eligible for subsequent C−C coupling reactions.

Macrolactonisation of a suitable heptapeptide precursor provides the cyclic depsipeptide core of callipeltin A in excellent yield.

Both paralogs of the calcium-dependent activator protein for secretion (CAPS) are required for exocytosis of synaptic vesicles (SVs) and large dense core vesicles (LDCVs). Despite approximately 80% sequence identity, CAPS1 and CAPS2 have distinct functions in promoting exocytosis of SVs and LDCVs in dorsal root ganglion (DRG) neurons. However, the molecular mechanisms underlying these differences remain enigmatic. In this study, we applied high- and super-resolution imaging techniques to systematically assess the subcellular localization of CAPS paralogs in DRG neurons deficient in both CAPS1 and CAPS2. CAPS1 was found to be more enriched at the synapses. Using – in-depth sequence analysis, we identified a unique CAPS1 N-terminal sequence, which we introduced into CAPS2. This CAPS1/2 chimera reproduced the pre-synaptic localization of CAPS1 and partially rescued synaptic transmission in neurons devoid of CAPS1 and CAPS2. Using immunoprecipitation combined with mass spectrometry, we identified CAPS1-specific interaction partners that could be responsible for its pre-synaptic enrichment. Taken together, these data suggest an important role of the CAPS1-N terminus in the localization of the protein at pre-synapses.